1. Field of the Invention
The present invention relates to cryogenic fluids. In another aspect, the present invention relates to methods and apparatus for processing, transporting and/or storing cryogenic fluids. In even another aspect, the present invention relates to receiving and/or dispensing terminals for cryogenic fluids and to methods of receiving, dispensing and/or storing cryogenic fluids. In still another aspect, the present invention relates a cryogenic fluid system having a floating liquefaction unit receiving a gas from a source, a shuttle vessel for carrying liquefied gas away from the liquefaction unit, and a floating regasification unit for receiving the liquefied gas from the vessel, regassifying the liquefied gas and providing the gas to a distribution system.
2. Description of the Related Art
Most conveniently, natural gas is transported from the location where it is produced to the location where it is consumed by a pipeline. However, given certain barriers of geography, economics, and/or politics, transportation by pipeline is not always possible, economic or permitted. Without an effective way to transport the natural gas to a location where there is a commercial demand, the gas may be burned as it is produced, which is wasteful or reinjected into a subsurface reservoir which is costly and defers the utilization of the gas.
Liquefaction of the natural gas facilitates storage and transportation of the natural gas (a mixture of hydrocarbons, typically 65 to 99 percent methane, with smaller amounts of ethane, propane and butane). When natural gas is chilled to below its boiling point (in the neighborhood of −260° F. depending upon the composition) it becomes an odorless, colorless liquid having a volume which is less than one six hundredth (1/600) of its volume at ambient atmospheric surface temperature and pressure. Thus, it will be appreciated that a 50,000 cubic meter LNG tanker ship is capable of carrying the equivalent of 1.1 billion cubic feet of natural gas.
When LNG is warmed above its boiling point, it boils reverting back to its gaseous form.
The growing demand for natural gas has stimulated the transportation of LNG by special tanker ships. Natural gas produced in remote locations, such as Algeria, Malaysia, Brunei, or Indonesia, may be liquefied and shipped overseas in this manner to Europe, Japan, United States, or neighboring countries needing gas. Typically, the natural gas is gathered through one or more pipelines to a land-based liquefaction facility. The LNG is then loaded onto a tanker equipped with cryogenic compartments (such a tanker may be referred to as an LNG carrier or “LNGC”) by pumping it through a relatively short pipeline. After the LNGC reaches the destination port, the LNG is offloaded by cryogenic pump to a land-based regasification facility, where it may be stored in a liquid state or regasified. If regasified, the resulting natural gas then may be distributed through a pipeline system to various locations where it is consumed.
Of the known liquid energy gases, liquid natural gas is the most difficult to handle because it is so intensely cold. Complex handling, shipping and storage apparatus and procedures are required to prevent unwanted thermal rise in the LNG with resultant regassification. Storage vessels, whether part of LNG tanker ships or land-based, are closely analogous to giant thermos bottles with outer walls, inner walls and effective types and amounts of insulation in between.
A number of patents disclose transportation of cryogenic fluids.
U.S. Pat. No. 3,830,180, issued Aug. 20, 1974 to Bolton, discloses a ship for the transportation of volatile liquids having holds which contain a number of elongated vessels for containing cargo fluids where each vessel has a primary barrier for isolating cargo fluids from the hull and an insulating wall.
U.S. Pat. No. 4,317,474, issued Mar. 2, 1982 to Kentosh, describes a mooring and cargo transfer terminal for use in transferring a fluid such as LNG (liquified natural gas) which is supercooled and therefore likely to cause severe icing of pipes and joints. The terminal includes a table support in the form of a tower extending from a base at the sea floor up to the sea surface, and a table device rotatable about a vertical axis at the top of the table support. The table device carries a pair of fenders that can press directly against the side of a ship, hawser couplings for tying the table device to a set of hawsers that hold it tightly against the ship, and one or more loading arms which can extend beyond the table device to connect to an LNG coupling on the ship. A pipe carries LNG from an underwater pipeline up to a fluid swivel at the top of the table support, and the rotatable portion of the fluid swivel connects to the loading arms to deliver the LNG thereto. The direct abutment of the rotatable table with the side of a ship near the bow thereof, enables loading arms of minimal length to be utilized to carry the LNG to the ship.
U.S. Pat. No. 4,202,648, issued May 13, 1980 to Kvamsdal, discloses a floating plant for offshore liquefaction, temporary storage and loading of LNG, made as a semi-submersible platform with storage tanks for LNG arranged in the submerged section of the platform. The storage tanks are independent spherical tanks which are supported inside the submerged section of the platform and completely surrounded thereby.
U.S. Pat. No. 6,085,528, issued Jun. 11, 2000, Woodall et al, discloses an improved system for processing, storing, and transporting LNG, and describes containers and transportation vessels for storage and marine transportation of pressurized liquefied natural gas (PLNG) at a pressure in the broad range of about 1035 kPa (150 psia) to about 7590 kPa (1100 psia) and at a temperature in the broad range of about −123.degree. C. (−190.degree. F.) to about −62.degree. C. (−80.degree. F.). Containers described in the PLNG Patent are constructed from ultra-high strength, low alloy steels containing less than 9 wt % nickel and having tensile strengths greater than 830 MPa (120 ksi) and adequate toughness for containing PLNG.
U.S. Pat. No. 6,460,721, issued Oct. 8, 2002 to Bowen et al., discloses systems and methods for producing and storing pressurized liquefied natural gas (PLNG), wherein the systems and methods include (a) a natural gas processing plant suitable for producing PLNG; and (b) at least one container suitable for storing the PLNG, the at least one container comprising (i) a load-bearing vessel made from a composite material and (ii) a substantially non-load-bearing liner in contact with the vessel, said liner providing a substantially impermeable barrier to the PLNG. The systems and methods also preferably include (c) means for transporting the at least one container containing PLNG to an import terminal.
U.S. Pat. No. 6,560,988, issued May 13, 2003 to Kimble, describes systems and methods for delivering pressurized liquefied natural gas to an import terminal equipped with containers and vaporization facilities suitable for conventional LNG. The pressurized liquefied natural gas cargo, or any fraction thereof, is converted into conventional liquefied natural gas and sent to storage tanks suitable for conventional liquefied natural gas. Any of the cargo not converted to conventional liquefied natural gas can be compressed and warmed to pipeline specifications. This gas can then pass into a sendout pipeline.
U.S. Pat. No. 6,637,479, issued Oct. 28, 2003 to Eide, et al., discloses a system for offshore transfer of liquefied natural gas between two vessels. The system comprises a coupling head mounted at one end of a flexible pipe means and arranged for attachment on a platform at one end of one vessel when it is not in use, and a connection unit mounted at one end of the other vessel and comprising a pull-in funnel shaped for guided pull-in of the coupling head to a locking position in which the pipe means can be connected to transfer pipes on the other vessel via a valve means arranged in the coupling head. The coupling head is provided with a guide means and is connected to at least one pull-in wire for guided pull-in of the coupling head into the connection unit by a winch means an the other vessel.
All of the patents cited in this specification, are herein incorporated by reference.
However, in spite of the above advancements, there still exists a need in the art for apparatus and methods for processing, transporting, and/or storing LNG.
This and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.